1. Field of the Invention
The present invention relates to absorbent materials, and, more particularly, to compositions useful as animal litters.
2. Description of Related Art
The idea of using ground clay as an absorbent material in cat litter boxes dates from 1947, when "Kitty Litter" was invented to replace sand or ashes. At present, clay-based products are purported to account for more than 95% of the cat litter industry (Cat Fancy, October, 1994, p. 12).
Clay compositions vary depending upon the site from which it is mined. Generally, clay comprises inorganic materials composed primarily of anhydrous aluminum silicates in which a certain amount of magnesium, iron, alkali metals such as sodium or potassium, or alkaline earths such as calcium may be present. These clays occur predominantly as particles of size 2 micrometers or less and exhibit a net negative charge and plasticity when mixed with water. The clay minerals comprise the groups kaolin; talc pyrophyllite; smectite, including calcium montmorillonite and the expansive clay bentonite; vermiculite; true mica; brittle mica; chlorite; and variable clays as identified by the Nomenclature Committee of the Clay Minerals Society (R. T. Martin, 1991, Report of the clay minerals society nomenclature committee; Revised classification of clay minerals, Clay and Clay Minerals, Vol. 39, No. 3, pp. 333-35, as references in Fundamentals of Soil Behavior, Second Edition, J. K. Mitchell, p. 26, John Wiley & Sons, Inc., 1993). Also included are chain-structured clays such as sepiolite and attapulgite. The clumping properties of the clay may be adjusted by controlling the absorbency and mesh size.
The control of odor is also-an important criterion for animal litters. Absorbency is also important here, but it is also known to add a masking agent or antibacterial to control odor.
In addition to clay-based litters, it is also known in the art to utilize wood products, such as in the form of cedar chips (Cedar Lite, Cedrus International) or pellets made from the resin of heated ground aspen sawdust and bark (Gentle Touch Cat Litter, Gentle Touch Corp.). A mixture of cedar material and an alfalfa binder has been disclosed by Fry (U.S. Pat. No. 3,941,090), and an animal litter containing cedar in particulate form for cooperation with an absorbent soil, such as diatomaceous earth and clays is taught by Harsh et al. (U.S. Pat. No. 4,386,579). Pellets made from a mixture of poplar wood and peat are described by Bilings (U.S. Pat. No. 5,271,355).
Paper-based products are also known in the art. Pellets made from recycled paper are marketed as Bio-Flush Cat Litter (Ampro Industries), and short paper fibers from recycled paper are processed into Care Fresh Cat Litter (Absorption Corp.).
Vegetative products are also usable as absorbent materials. For instance, grain-based cat litters are known in the form of pellets (Cat Works, Absorption Corp.) and ground wheat products (Litter Mate, Productive Alternatives). Corncob litter is marketed as FieldFresh (The Andersons, Maumee, Ohio) and Cobby Cat (Sun Seed Co.). Pressed and dried citrus peels are made into CitraFresh (Blossom Products Co.), and pellets of ground straw grasses become Cat Country (Mountain Meadows).